Republican Sen. Thom Tillis of North Carolina said President Donald Trump’s decision to ease sanctions on Russia to allow diesel fuel exports could violate federal law, noting that Congress has not changed restrictions imposed after Russia invaded Ukraine.

Trump announced that Russia would release hundreds of thousands of tons of diesel fuel onto the global market, with additional supplies expected, drawing criticism from Ukraine and opponents of the administration’s policy.

Tillis warned that the arrangement could put American lives at risk, citing Russia’s support for mercenaries and its relationship with Iran, and suggested the issue could affect his support for upcoming government funding measures.

Rep. Thomas Massie of Kentucky defended Trump’s decision, arguing that sanctions contribute to higher U.S. prices and calling for restrictions on other petroleum products and raw metals to be lifted, NBC News has reported.

Tillis also criticized the Pentagon’s plan to livestream the execution of Fort Hood shooter Nidal Hasan, warning that the broadcast could help terrorist groups recruit supporters and renewing his call for Defense Secretary Pete Hegseth to leave his position.